Prevention of asthma: where are we in the 21st century?

Abstract

Asthma is the most common chronic disease of childhood and, in the latter part of the 20th century, reached epidemic proportions. Asthma is generally believed to result from gene-environment interactions. There is consensus that a ‘window of opportunity’ exists during pregnancy and early in life when environmental factors may influence its development. We review multiple environmental, biologic and sociologic factors that may be important in the development of asthma. Meta-analyses of studies have demonstrated that multifaceted interventions are required in order to develop asthma prevention. Multifaceted allergen reduction studies have shown clinical benefits. Asthma represents a dysfunctional interaction with our genes and the environment to which they are exposed, especially in fetal and early infant life. The increasing prevalence of asthma also may be an indication of increased population risk for the development of other chronic non-communicable autoimmune diseases. This review will focus on the factors which may be important in the primary prevention of asthma. Better understanding of the complex gene–environment interactions involved in the development of asthma will provide insight into personalized interventions for asthma prevention.

Keywords::

• allergens
• asthma
• children
• environment
• genes
• microbiota
• nutrition
• prevention
• stress

Financial & competing interests disclosure

A Becker is supported by CIHR, AllerGen NCE and NSERC-CHRP. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• • Asthma has become the most common chronic disease of childhood and has reached epidemic proportions in the past few decades.

• • The ‘hygiene hypothesis’ suggests that early exposure to microbiota may be beneficial against asthma development.

• • However, certain respiratory viral illnesses during early life have been associated with an increased likelihood for asthma. Most recently, wheezing episodes with human rhinovirus, rather than respiratory syncytial virus, have been shown to be highly associated with persistent asthma.

• • Pollutants, especially tobacco smoke, are associated with an increased risk for asthma.

• • The beneficial effect of breastfeeding on asthma prevention is controversial and caution should be taken into account when advising families that breastfeeding will prevent asthma. However, breastfeeding should be encouraged for all of its other benefits.

• • There is no reason to delay solid foods beyond 4–6 months of life and early introduction of some solids may prevent allergy to that food.

• • Early life exposure to pets has not been associated with prevalence of asthma. In fact, dogs in the home may be associated with less asthma.

• • Antibiotic use and paracetamol intake in early life may be associated with an increased risk of asthma.

• • Stress in early life has been associated with more asthma.

• • Multifaceted interventions have been shown to be effective in the prevention of asthma, whereas single interventions (e.g., eliminating dust mite exposure) have not worked.

Notes